I don't think so. Reproducible builds means that compiling the binary packages results in byte-by-byte identical copies, even when done on different machines at different times: the packaging sources do not get any simpler (to the contrary, they may get slightly more complex due to additional concerns).

The XDG App effort to produce standardized runtimes and isolated applications is probably what you're looking for, but it is completely orthogonal to reproducible builds as runtimes for XDG App can be built in a multitude of ways, eg. with pre-built distribution packages (reproducible or not).